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Biomedical subjects

G Kohler

Publications and source records attributed to G Kohler.

At least 19 recordsLinked to original sources
PubMed2004

Inter-observer agreement of ultrasonographic measurement of alpha and beta angles and the final type classification based on the Graf method.

BACKGROUND: The aim of our study was to investigate the agreement of the assessment of hip ultrasonograms by different observers. METHODS: In the period from June 3rd to December 9th 2002, four different (by experience and field) groups of observers rated all first time sonograms obtained in our hospital. The results in terms of angle and type classification were compared. RESULTS: 158 ultrasonographic images were evaluated. The inter-observer agreement for the classification "normal" (type I) versus "abnormal" (types IIa+ to IV) varied from 83% to 90% with kappa coefficients which indicated moderate (kappa 0.55) to substantial (kappa 0.71) inter-observer agreement. For one pair of observers, a better agreement could be demonstrated for the assessment of immature hips than for mature ones. The deviation for the a-angle was 0 to 16 degrees with a standard deviation of 3.15 degrees (95% CI 2.95, 3.37), and for the b-angle 0 to 26 degrees with a standard deviation of 6.1 degrees (95% CI 5.7, 6.5). The intra-class correlation coefficient was estimated to be 0.72 and 0.34 for the alpha and beta angles respectively. If the hip was immature there was no increase in the discrepancy in assessment between observers. The least agreement existed between the less experienced and the most experienced. It has not been possible to make a statement on the discrepancy with regard to initial signs of instability or decentralization of the hip joints because of the small number of hips of this type. CONCLUSIONS: Although the spread in measured a- and b-angles is large, the inter-observer agreement for the classification showed good results. No disagreement occurred in the diagnosis of normal vs. dysplastic hips, so no severe cases have been missed. The experience and training of the investigators seemed to play an important role with regard to variability and agreement. The agreement in the assessment of immature hips was better than that of mature hips. Therefore, ultrasound examination of infant hips would appear to be a trustworthy screening method.

Analysis of Variance↗
PubMed2003

Experiences in diagnosis and treatment of hip dislocation and dysplasia in populations screened by the ultrasound method of Graf.

Ultrasound investigation of the hip according to Graf is performed, whenever possible, as a routine screening test for hip dysplasia and dislocation in neonates. However, in spite of screening, hip dysplasia and/or dislocation is identified in a number of children after the third month of life only. The present study presents an analysis of reasons and causes. Between August 1999 and July 2001 children aged between six months and five years were documented, in whom the diagnosis of hip dysplasia or dislocation was made, despite normal ultrasound findings at primary investigation and who required non operative or operative treatment by a specialist surgeon working in Switzerland in paediatric orthopaedics. The study included 26 children (17 girls / 9 boys). Hip dysplasia and/or dislocation was diagnosed between the age of 6 days and 41 months. Twelve children had to be excluded from the sample (n = 26), four were infants who had basic neurological disorders or multiple anomalies and there were eight children from abroad whose original documentation could not be obtained. Analysis of the remaining 14 children showed that 43% were misdiagnosed (n = 6) and a treatment error occurred in 36% (n = 5) of cases. One child presented with a teratogenic hip dislocation. In two other infants with normal primary ultrasound findings, hip dysplasia was identified radiographically once the child started to walk. Delayed diagnosis can be the result of technical errors or misinterpretation. The six patients meeting the criteria of misinterpretation can be expressed as a rate of 0.04% of all births. However, even if the disorder is correctly diagnosed, its identification and treatment may be inadequate or fail to produce the desired results. This was the case for five of the children, that is, for a rate of 0.03% of births.

Bone Diseases, Developmental↗
PubMed2003

Does it always have to be Perthes' disease? What is epiphyseal dysplasia?

The epiphyseal dysplasias are classified as osteochondral dysplasias in a heterogeneous group of skeletal dysplasias. The common feature of these hereditary conditions is short stature attributable to skeletal dysplasia at various sites. Multiple epiphyseal dysplasia and spondyloepiphyseal dysplasia are of interest to the authors, because the two syndromes are similar in their morphologic features and at first glance suggest the diagnosis of Perthes' disease. Spondyloepiphyseal dysplasia (Wiedemann-Spranger syndrome) is a disorder of growth in which there is an abnormality of enchondral ossification affecting the vertebral bodies and the epiphyses of the long bones. The two forms are the more severe congenita form (Type I), which is inherited as an autosomal dominant condition and is associated with a highly disproportional reduction in growth and severe coxa vara, and the milder tarda form which is an X-linked recessive condition, in which growth in adolescence is defective after normal childhood development. Multiple epiphyseal dysplasia is an abnormality of enchondral ossification, especially of the femoral head epiphysis, and it is an autosomal dominant condition. Depending on its severity, a distinction is made between the severe Fairbank form, the milder Ribbing form, and a mild localized Meyer form.

Adolescent↗
PubMed1998

Heat-induced segmental necrosis after reaming of one humeral and two tibial fractures with a narrow medullary canal.

In three cases referred to our clinic (a simple fracture of the humeral shaft, a simple, closed fracture, and a wedge fracture of the mid-third of the tibia), bone necrosis had resulted from excessive heat produced by reaming extremely narrow medullary cavities (5-5.5 mm diameter) with the 9 mm front-cutting reamer as part of a reamed nailing procedure. In any one case, different degrees of damage can occur from the metaphysis to the diaphysis. Based on the clinical course and the histological evaluation, we postulate that heat-induced damage can be divided into four degrees of severity (0-3): Grade 0: no damage; no devascularization, no heat-induced damage. Grade 1: The heat damaged zone is cut away during subsequent reaming, the only damage is devascularization. Grade 2: The damaged zones are not eliminated by subsequent reaming. The bone is devascularized and heat damaged. Grade 3: The entire cross section of the bone including the periosteum is devitalized by exposure to excessive heat. Depending on the severity of additional damage to the soft tissues, grave consequences are to be expected and further operations are unavoidable. The effects of heat-induced damage are particularly critical in the presence of infection (cases 2 and 3). The fundamental aspects and the extent of heat necrosis will be discussed. After discussion with the AO Technical Commission on the cause of heat-induced necrosis, we would recommend the following preventive measures: 1. preoperative measurement of the smallest diameter of the medullary cavity in two planes. 2. reaming with the standard instrumentation (9 mm) only if the medullary cavity has a diameter of at least 8 mm at its narrowest point. 3. Extremely narrow cavities should first be reamed manually or an alternative to nailing should be sought. 4. It is strongly recommended that only sharp reamers be used in such cases and blunt or damaged reamers replaced.

Adult↗
PubMed1998

The physics of heat generation during reaming of the medullary cavity.

Clinical experience of special cases of reaming of a small diameter medullary cavity has shown a remarkable temperature increase with associated thermal damage to the surrounding tissue. By applying known solutions of the heat conductivity equation to simplified models of a reamer to bone tube system, the effects of the most important parameters on heat generation and temperature distribution are explained. The results allow a quantitative assessment of reaming techniques for small cavities which gives rise to the following recommendations: reamers used consecutively should not increase more than 0.5 mm in diameter; blunt instruments must be replaced or sharpened; prepare very narrow medullary cavities with the small diameter hand reamer; if the reamer ceases to advance do not increase the axial force but withdraw it and check the reamer and the temperature. Cooling, cleaning and replacement of the reamer should be considered, if appropriate.

Biophysical Phenomena↗
PubMed1998

Further studies on HTLV-I associated myelopathy in Argentina.

We report 10 HTLV-I virus seropositive subjects, eight of them with HTLV-I associated myelopathy (HAM), two of them also infected with HIV as well as two asymptomatic HTLV-I+ relatives of two unrelated patients. HTLV-I is endemic in several tropical areas, where it causes different neurological diseases. Only few patients have been reported in our country since 1994. We studied 8 patients, who fulfilled the clinical criteria for chronic spastic paraplegia, and 2 other non-symptomatic HTLV-I seropositive relatives, with electromyography (EMG), motor and sensory conduction velocities (NCV), somatosensory, visual and brainstem auditory evoked potentials (SSEP, VEP and BAEP), Magnetic Resonance Images (MRI) and cerobrospinal fluid (CSF) analysis. The latter was carried out only in seven symptomatic patients. In every case positive ELISA tests for HTLV-I/II were confirmed by Western Blot. The two asymptomatic persons were clinically and electromyographically assessed, one of them was also submitted to SSEPs studies. Three patients were males. Patient's ages ranged from 5 to 65 years old. All symptomatic patients showed muscular weakness, spasticity with pyramidal signs and sphincter disturbances. Five of them had paresthesias and 2 had burning pain on their feet. The EMGs and the NCVs were normal in 7 patients and in the 2 asymptomatic ones. SSEPs, obtained by stimulating the posterior tibial nerves, were impaired in 7 patients and in the asymptomatic person who received the procedure. The 7 symptomatic patients who underwent lumbar puncture had positive tests for HTLV-I in CSF, 3 out of these 7 patients had also high protein levels and 4 had increased number of lymphocytes. In 2 patients intrathecal IgG production could also be demonstrated. MRI were normal in 7 patients and in the 2 asymptomatics, the exception being a female who had bilateral hyperintense lesions in cerebral white matter in T2. In conclusion, tropical spastic paraparesis is apparently a rare disorder in Argentina. However, some cases have been reported recently. Most probably, its prevalence is currently underestimated. Its diagnosis should be considered in every patient with progressive spastic paraplegia.

Adult↗
PubMed1996

Gasless Laparoscopic-Assisted Radical Vaginal Hysterectomy with Lymphadenectomy for Cervical Carcinoma

We performed gasless lymph node dissection in a woman with cervical carcinoma FIGO stage Ib. The dissection of the parametrium was done vaginally by hysterectomy including the Schuchardt incision and the removal of 2 cm of vagina. We removed 45 lymph nodes. For the laparoscopic procedures we used a Laparofan and Laparolift (Origin Medsystems). The estimated blood loss was 250 ml and operative time 330 minutes. An advantage of the gasless method is that one can use endoscopic and conventional instruments. We combined advantages of laparoscopy (good visibility, enlargement of blood and lymph vessels) and of the gasless method (use of the same instruments as in laparotomy, quick change of endoscopic and conventional instruments without gas loss). This technique achieves the same surgical results as radical laparotomy in selected women with cervical carcinoma.

Journal Article↗
PubMed1996

Schistosoma mansoni in IL-4-deficient mice.

Immunopathology and immune responses to Schistosoma mansoni were examined in IL-4 -/- mice. IL-5 and IL-10 production by lymphoid cells stimulated with soluble egg antigen (SEA), peripheral eosinophilia and serum levels of soluble IL-4 receptor but not IgE were all significantly elevated over background normal levels in IL-4 -/- mice as a result of infection. Additionally, IL-10 and IL-5 in addition to IL-2 and IFN-gamma transcripts were equally evident in diseased liver tissue from infected IL-4 -/- and wild-type mice. Nevertheless, analysis of antigen-stimulated IL-2, IL-4, IL-5, IL-10 and IFN-gamma production by lymphoid organ cells from infected or egg-injected IL-4 -/- mice revealed a more Th1-like pattern of cytokine production (IFN-gamma > IL-5) than in (wild-type) mice in which a stronger type 2 response to SEA was detectable (IL-4, IL-5 > IFN-gamma). Despite this, at 8 and 16 weeks after infection, liver pathology, as indicated by the size, cellularity, cellular composition and collagen content of granulomas, was similar in IL-4 -/- and wild-type animals. As in wild-type animals, granuloma size at week 16 was smaller than at week 8, indicating that modulation had occurred in the absence of IL-4. Differences in pathology were seen only when eggs were experimentally embolized to the lungs, in which case IL-4 -/- mice made smaller granulomatous responses than did wild-type animals. These data clearly show that IL-4 is not necessary for the hepatic granuloma formation which occurs during experimental schistosomiasis.

Animals↗
PubMed1996

Topical treatment of life threatening haemoptysis from aspergillomas.

BACKGROUND: The efficacy of topical treatment of 12 episodes of severe life threatening haemoptysis from a pulmonary aspergilloma in 11 patients is reviewed. METHODS: A retrospective review was performed on five white and six African-American patients of mean age 49 years. The underlying diseases were bronchiectasis, sarcoidosis, tuberculosis, or histoplasmosis. The patients were prospectively considered poor surgical risks because they had a forced expiratory volume in one second (FEV1) of < 50% predicted and an arterial oxygen tension (PaO2) of < 7.95 kPa breathing room air. As surgical intervention was not possible, local intracavitary instillation of sodium or potassium iodide was performed. Two patients were previously treated with amphotericin B. In one patient sodium iodide alone was used and in the remaining eight potassium iodide alone was instilled. The transcricothyroid approach was used in six patients and the percutaneous approach in five. RESULTS: Haemoptysis ceased within 72 hours in all patients after the instillation of sodium or potassium iodide. There was no morbidity or mortality, and side effects included slight irritation on instillation of the iodide solution and occasional cough which was easily controlled. All patients were alive at least one year later. CONCLUSION: Intracavitary treatment is a viable option in the poor risk patient with life threatening haemoptysis from an aspergilloma.

Adult↗
PubMed1996

[Acute isolated ventral dislocation of the head of the fibula].

We present the case of a 19-year-old soccer player who had sustained a valgus, external rotation trauma to the flexed knee with traumatic anterolateral dislocation of the proximal tibiofibular joint and concomitant partial peroneal nerve palsy, which went away within a few days. We discuss the clinical features and treatment by temporary screw fixation of the proximal tibiofibular joint, as well as the results in the literature where predominantly conservative treatment is reported.

Adult↗
PubMed1995

Persistent elevation of inflammatory cytokines predicts a poor outcome in ARDS. Plasma IL-1 beta and IL-6 levels are consistent and efficient predictors of outcome over time.

BACKGROUND: Inflammatory cytokines have been related to the development of adult respiratory distress syndrome (ARDS), shock, and multiple organ dysfunction syndrome (MODS). We tested the hypothesis that unfavorable outcome in patients with ARDS is related to the presence of a persistent inflammatory response. For this purpose, we evaluated the behavior of inflammatory cytokines during progression of ARDS and the relationship of plasma inflammatory cytokines with clinical variables and outcome. METHODS: We prospectively studied 27 consecutive patients with severe medical ARDS. Plasma levels of tumor necrosis factor alpha (TNF-alpha) and interleukins (ILs) 1 beta, 2, 4, 6, and 8 were measured (enzyme-linked immunosorbent assay [ELISA] method) on days 1, 2, 3, 5, 7, 10, and 12 of ARDS and every third day thereafter while patients were receiving mechanical ventilation. Subgroups of patients were identified based on outcome, cause of ARDS, presence or absence of sepsis, shock, and MODS at the time ARDS developed. Subgroups were compared for levels of plasma inflammatory cytokines on day 1 of ARDS and over time. RESULTS: Of the 27 patients, 13 survived ICU admission and 14 died (a mortality rate of 52%). Overall mortality was higher in patients with sepsis (86 vs 38%, p < 0.02). The mean initial plasma levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 were significantly higher in nonsurvivors (p < 0.0001) and in those patients with sepsis (p < 0.0001). Plasma levels of IL-1 beta (p < 0.01) and IL-6 (p = 0.03) were more strongly associated with patient outcome than cause of ARDS (p = 0.8), lung injury score (LIS), APACHE II score, sepsis (p = 0.16), shock, or MODS score. Plasma levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 remained significantly elevated over time (p < 0.0001) in those who died. Although it was the best early predictor of death (p < 0.001), plasma IL-2 > 200 pg/mL lost its usefulness after the first 48 h. A plasma IL-1 beta or IL-6 level > 400 pg/mL on any day in the first week of ARDS was associated with a low likelihood of survival. CONCLUSIONS: Our findings indicate that unfavorable outcome in acute lung injury is related to the degree of inflammatory response at the onset and during the course of ARDS. Patients with higher plasma levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 on day 1 of ARDS had persistent elevation of these inflammatory cytokines over time and died. Survivors had lesser elevations of plasma inflammatory cytokines on day 1 of ARDS and a rapid reduction over time. Plasma IL-1 beta and IL-6 levels were consistent and efficient predictors of outcome.

Adult↗
PubMed1995

Inflammatory cytokines in the BAL of patients with ARDS. Persistent elevation over time predicts poor outcome.

BACKGROUND: Inflammatory cytokines (ICs) are important modulators of injury and repair. ICs have been found to be elevated in the BAL of patients with both early and late ARDS. We tested the hypothesis that recurrent injury to the alveolocapillary barrier and amplification of intra-alveolar fibroproliferation observed in nonresolving ARDS is related to a persistent inflammatory response. For this purpose, we obtained serial measurements of BAL IC and correlated these levels with lung injury score (LIS), BAL indexes of endothelial permeability (albumin, total protein [TP]), and outcome. METHODS: We prospectively studied 27 consecutive patients with severe medical ARDS. Using enzyme-linked immunosorbent assay methods, levels of tumor necrosis factor-alpha (TNF-alpha) and interleukins (IL) 1 beta, 2, 4, 6, and 8 were measured at frequent intervals in both plasma and BAL. In 22 patients, bilateral BAL was obtained on day 1 of ARDS and at weekly intervals when possible. Right and left BALs were analyzed separately for IC levels, total cell count and differential, albumin, TP, and quantitative bacterial cultures. RESULTS: On day 1 of ARDS, the 10 nonsurvivors had significantly higher (p = 0.0002) BAL TNF-alpha, IL-1 beta, IL-6, and IL-8 levels, which remained persistently elevated over time, indicating a continuous injury process. In contrast, the 12 survivors had a lesser elevation and a rapid reduction over time. Initial BAL IL-2 and IL-4 levels were significantly higher in patients with sepsis (p = 0.006); both increased over time in survivors and nonsurvivors. BAL levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 correlated with BAL albumin and TP concentrations but not with LIS or ratio of arterial oxygen tension to inspired oxygen concentration. BAL: plasma ratios were elevated for all measured cytokines, suggesting a pulmonary origin. On day 1 of ARDS, nonsurvivors had significantly higher (p = 0.04) BAL: plasma ratios for TNF-alpha, IL-1 beta, IL-6, and IL-8. Over time, BAL:plasma ratios for TNF-alpha, IL-1 beta and IL-6 remained elevated in nonsurvivors and decreased in survivors. CONCLUSIONS: Our findings indicate that an unfavorable outcome in ARDS is associated with an initial, exaggerated, pulmonary inflammatory response that persists unabated over time. Plasma IC levels parallel changes in BAL IC levels. The BAL:plasma ratio results suggest, but do not prove, a pulmonary origin for IC production. BAL TNF-alpha, IL-1 beta, and IL-8 levels correlated with BAL indices of endothelial permeability. In survivors, reduction in BAL IC levels over time was associated with a decline in BAL albumin and TP levels, suggesting effective repair of the endothelial surface. These findings support a causal relationship between degree and duration of lung inflammation and progression of fibroproliferation in ARDS.

Adult↗
PubMed1994

[Cerebellar syndrome caused by amiodarone].

Amidarone (AMD) is an antiarrhythmic drug with side effects on the nervous system. Cerebellum is seldom involved: We describe the case of a 56 years old male patient with a history of 4 month of cerebellar involvement characterized by gait unsteadiness, ataxia, nistagmus and vertigo. He was on treatment with AMD because of ventricular arrythmia. The cerebellar syndrome progressively disappeared after drug withdrawal and he was symptoms-free 4 months later. Similar symptoms appeared after another one month of automedication with the same drug. Structural lesions, metabolic, nutritional deficiencies or toxics were excluded. Mechanisms of cerebellar toxicity of AMD are yet unknown. The knowledge of the toxic effects of this drug, widely used in our country, would allow its early recognition.

Amiodarone↗
PubMed1992

[Cerebral embolism of cardiac origin].

We reviewed 538 charts of patients hospitalized with acute ischemic strokes between 1983 and 1991. The inclusion criteria for cardioembolism were: 1) sudden onset and maximal neurological focal deficit from the beginning, 2) brain CT showing an ischemic infarct, hemorrhagic infarct, or multiple infarcts, 3) cardioembolic sources demonstrated by echocardiography or heart catheterization, and 4) absence of stenotic-occlusive cerebrovascular disease. Sixty-nine patients (12.8%) filled the criteria for cardiogenic brain embolism. Cardiac sources were: 1) nonvalvular atrial fibrillation in 20 patients (29.0%), 2) rheumatic heart disease in 14 (20.3%), 3) nonischemic dilated cardiomyopathy in 13 (18.8%). Nine of these (69%) had cardiac involvement due to Chagas' disease, 4) ischemic heart disease in 11 (15.9%), and 5) other less common conditions such as bacterial endocarditis, mitral valve, and congenital heart malformation in 11 (15.9). Transient ischemic attacks preceding stroke occurred in 11 patients (15.9%), six patients had previous strokes, and 14 patients (20.3%) had silent infarcts. Early recurrence of embolism (three initial weeks) occurred in 5 patients (7.2%), and 28.6% of the patients had hemorrhagic transformation within this period. Taken together, our figures show that, although they are well in line with the current literature, nonischemic dilated cardiomyopathy is one of the main causes of cerebral embolism in our community. This reflects the presence of a regional factor, namely Chagas' disease.

Adult↗
PubMed1989

An acidic fibroblast growth factor stimulates DNA synthesis, inhibits collagen and alkaline phosphatase synthesis and induces resorption in bone.

We have examined the effects of an acidic fibroblast growth factor (aFGF) on bone cell growth and differentiation and on osteoclastic resorption using rat fetus organ cultured calvariae and long bones, respectively. Low concentrations of this aFGF stimulated DNA synthesis (1.28 ng/ml) and inhibited collagen formation (1.28 ng/ml) and alkaline phosphatase activity (0.64 ng/ml) in the isolated calvariae. The inhibition of collagen synthesis was independent of the aFGF's mitogenic effect, and was evident in periosteum-containing and periosteum-free bones, pointing to osteoblasts as the aFGF-responsive cells. Our preparation of aFGF enhanced resorption in the long bones by a calcitonin-inhibitable mechanism. PGE2 release accompanied and indomethacin prevented the enhancement of resorption. By contrast, indomethacin did not block the stimulation of DNA and collagen synthesis caused by our aFGF. These results indicate that our aFGF exerts a PGE2-independent effect on DNA synthesis and collagen synthesis and a PGE2-dependent effect on resorption in bone tissue in vitro.

Alkaline Phosphatase↗
PubMed1988

Bone-resorbing agents promote and interferon-gamma inhibits bone cell collagenase production.

Parathyroid hormone, prostaglandin E2, 1 alpha,25-dihydroxyvitamin D3, interleukin-1, tumor necrosis factor alpha, and epidermal growth factor, all known stimulators of bone resorption, markedly enhanced collagenase secretion by rat fetus osteoblastlike cells in primary culture as judged by enzyme-linked immunosorbent assay. Untreated cells contained no immunostainable or extractable collagenase. Collagenase was detected in the treated cells and media only after 1-3 h of treatment, and there was no increment in collagenase activity when cells were treated in the presence of actinomycin D or cycloheximide. Cells secreted collagenase in a latent form and also elaborated collagenase inhibitor; chromatographic separation of collagenase from collagenase inhibitor and subsequent activation of the collagenase with trypsin yielded the active species in stimulated but not in unstimulated cells. The ability of individual prostanoids, among seven tested, to promote collagenase production correlated positively with their reported capacity to promote bone resorption. Interferon-gamma (IFN-gamma), a known resorption inhibitor, blocked the increment in collagenase production caused by all agents tested. These results indicate a close linkage between stimulation of bone resorption and collagenase production by osteoblastlike cells. Various resorption stimulators, including some not previously tested for effects on collagenase, augment the de novo synthesis and secretion of collagenase and act by an IFN-gamma-inhibitable mechanism.

Animals↗
PubMed1986

Prostaglandins change cell shape and increase intercellular gap junctions in osteoblasts cultured from rat fetal calvaria.

Mounting experimental evidence indicates that osteoblasts may be cellular intermediaries in the local activation of bone remodeling. To elucidate the role of these cells in activation, we examined the effects of prostaglandins (PGs), known resorption stimulators, on cell shape and intercellular junctional relationships in osteoblasts cultured from rat fetal calvaria. Exposure to PGE2 and PGE1, promoters of bone resorption, rapidly (within 20 min) converted the osteoblasts from a flattened to a stellate shape (shape change), and markedly increased the appearance of intercellular (gap) junctions within 10 min. Both effects were directly related to the prostaglandin concentration, as little as 1 nM being effective. PGE1, but not PGB1, PGF1 alpha, PGD2, and PGF2 alpha, mimicked the substantial effect of PGE2 on shape change. Shape change and gap junction formation appear to arise independently. PTH, an inducer of shape change, did not affect the number of gap junctions appreciably. Colchicine, a microtubule polymerization inhibitor, and trifluoperazine, an inhibitor of calmodulin action, blunted PGE2-mediated shape change but not the effect of PGE2 on gap junctions. Shape change and gap junction formation may be important events in local activation, shape changes in surface osteoblasts serving to expose bone surfaces which are chemotactic for osteoclasts and gap junctions propagating locally initiated activation messages.

Animals↗